1. Field of the Invention
This invention relates generally to synthetic hydrocarbon resin compositions, their production, and their uses in printing ink compositions.
2. Summary of the Prior Art
Printing ink is a fluid or semifluid colored material consisting of a color body and a carrying vehicle. The carrying vehicle is necessary to distribute the color body on the printing press.
Rosin, modified rosin, and certain natural resins have been used extensively as carrying vehicles. However, the decrease in the availability of rosin and the increased use of printing inks has created an increasing need for a synthetic replacement for rosin in printing inks, especially rotogravure printing inks. Synthetic resins, especially synthetic hydrocarbon resins, may be used as synthetic replacements.
Such a synthetic resin must have the following properties.
1. high resin softening point, PA1 2. sufficient solubility in the printing ink solvent, PA1 3. fast drying speed, PA1 4. sufficient color dispersibility, PA1 5. fine gloss PA1 6. sufficient viscosity stability, and PA1 7. sufficient compatibility with printing ink additives.
Hydrocarbon resins suitable for a wide variety of end uses including printing ink compositions have been known for many years. See U.S. Pat. Nos. 2,598,424; 3,290,275; 3,299,034; 3,468,837; 3,523,095; 3,753,693; and 3,775,381; and "Recent Developments in Hydrocarbon Resins", K. E. Jackson, Official Digest, pp. 372-385, May 1956; and "Synthetic Resins for Inks", John P. Petrone, The American Ink Maker, Vol. 49 March - October 1971).
Printing ink additives such as ethyl cellulose and ethyl hydroxyethyl cellulose promote ink film adhesion, toughness, gloss, and scuff or rub resistance. Thus, it is necessary that the hydrocarbon resins used in printing inks be compatible with these additives. U.S. Pat. No. 3,753,963 discloses, in general, the production of a hydrocarbon resin, which resin is presently thought to be compatible with ethyl hydroxyethyl cellulose, but which resin lacks compatibility with ethyl cellulose.
Thus, the search has continued for new synthetic resins having improved properties, particularly in the printing ink industry which has searched for a suitable replacement for rosin and rosin derivatives in rotogravure printing ink compositions. The present invention was made as a result of this search.